Official stats underestimate brain injury

By Eleanor McDermid, Senior medwireNews Reporter

A population-based study suggests that the true incidence of traumatic brain injury (TBI) is about sixfold higher than official figures state.

"Our estimates are the first to include more mild cases of TBI that are not usually treated in hospital and, thus, are often overlooked in official estimates," said lead researcher Valery Feigin (Auckland University of Technology, New Zealand) in a press statement.

As reported in The Lancet Neurology, 95% of the 1369 TBI cases in the study were mild, and 64% of these were detected via hospitals. A further 8% were detected via the family doctor and 28% through other sources.

Feigin and colleagues used sources including hospitals, brain imaging records, family doctors, prisons, traffic accident records, coroner and autopsy records, and accident records of schools and sports centers. They also encouraged self-referrals to the study, by advertising it widely. They aimed to record all TBI cases that occurred over a 1-year period in a large urban area and the surrounding rural area in the North Island of New Zealand.

Even moderate or severe TBI cases were not all detected via hospitals, with 21% found through other sources. The most common causes of these TBIs were transport accidents and falls (both 39%), whereas falls (38%) and exposure to mechanical force (22%) were the most common causes of mild TBI. Assaults were also responsible for a substantial number of cases (14-17%).

The incidence of any TBI was 790 per 100,000 person-years, age-standardized to 811 per 100,000 person-years. From this, the team estimates that 54-60 million people worldwide have a TBI each year, with 2.2-3.6 million people having moderate or severe injury.

"This is almost six times higher than previous estimates and means that every second two people in the world are struck by a new TBI," said Feigin. Recent World Health Organization estimates are for 100-300 TBIs per 100,000 people per year.

"Our analysis raises some very important issues, in particular that healthcare policy and provision may be grossly inadequate for the huge and growing burden of TBI worldwide," she said. "More comparable population-based studies of TBI are urgently needed to inform effective treatment, prevention, and rehabilitation strategies."

Young people, aged up to 34 years, accounted for nearly 70% of all TBI cases, and TBI was most common in males than females. Moderate or severe TBI was more than twice as common in the rural populace than in urban dwellers.

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